This invention relates to visualizing and observing hydraulic flow conditions in a liquid flow stream; and in particular, it relates to a new and improved method and apparatus for accomplishing same.
Heretofore, techniques for observing hydraulic flow conditions have utilized introduction of air bubbles, plastic pellets, aluminum flakes, and the like, into the liquid flow streams. Photographic means have been used for recording and studying movement of the introduced ingredient. At low flow stream velocities, prior techniques have permitted fairly direct estimates of the liquid flow velocity, essentially by direct visual observation. However, above very low velocities, these techniques do not permit direct estimates of velocities by visual observation, and moreover they do not lend themselves to determining velocity by recording techniques such as videotape recording systems. Motion picture photography has also been used in the past. However, this procedure is very time consuming and obtaining meaningful results requires the tedious task of studying the film, frame by frame. When using the solid substances such as plastic pellets, aluminum flakes or the like, these had the advantage of providing greater visibility. However, these have the disadvantage that it is virtually impossible to clean the test loop to remove these solid substances and hence they cannot be used for tests requiring pure water.
Examples of prior patents which utilize gas bubbles in liquid for different purposes includes U.S. Pat. Nos. 2,967,450; 3,403,554; 3,942,371 and 4,084,432.
Hence, there exists a need for a technique which will allow improved direct observation of liquid flow conditions, including both direction and velocity.